The invention relates to the field of emitting devices, and in particular to a new type of light emitting devices based on the concept of surface phonon polariton (SPP).
There has been a need for mid-infrared and far-infrared light emitting devices for use in many applications such as sensing and imaging. Given the various gains in research and development, the use of such devices is more frequently seen in semiconductor quantum cascade lasers and terahertz frequency generations by ultra-short pulses. In quantum cascade lasers, the long wavelength emission is obtained by injected electron transition between the quantum-confined energy levels within the conduction band by carefully bandgap engineering. Strong loses of generated long wavelength emission in a semiconductor has to be accommodated by a cooling device to operate below room temperature. In terahertz generations, a bulky and strong short pulse laser is required.